Agricultural seeds are often treated with insecticides, fungicides, inoculants, and other compositions immediately before planting. The time window for planting—when the weather is warm enough and the fields are dry—is often very short. This means the seed dealer must quickly treat and deliver a high volume of seed to farmers who are ready to plant their fields. These seed treatments are commonly applied by spraying a liquid composition to the surface of seed, which requires a smaller quantity of seed treatment composition than the traditional field application of treatment fluids.
The last stage of treating seeds involves placing the wet, freshly treated seed in a rotating drum that mixes the treated seed, evenly distributes the treatment coat, and allows the treatment solution to dry. Seed progresses through the rotating drum in three phases: initial seed aggregation, mixing/drying, and cleanout. The initial seed aggregation phase is when wet, partially covered seed begins to enter the drum. The seed accumulates in the interior of the drum to form a seed aggregate in the bottom of the drum. During the mixing/drying phase the drum operates in steady state with seed entering through the inlet and discharging through the discharge end. The interior of the rotating drum lifts the seed up the side of the drum thereby mixing and distributing treatment across the surface of the individual seed. During the cleanout phase, no new seed enters the rotating drum. The drum is generally tilted, allowing gravity to encourage the seed for discharging at the discharge end.